PENANG, April 27 (Bernama) -- Malaysia's export of Light Emitting Diode (LED) products is expected to increase by 20 per cent this year, compared to 12 per cent in 2009.
International Trade and Industry Minister Datuk Seri Mustapa Mohamed said last year, the export of LED products amounted RM1.81 billion, an increase of 12 per cent from 2008.
"We are confident that the export of LED products will increase this year following the improving economic conditions," he told reporters, after the opening of OSRAM Opto Semiconductors (Malaysia) Sdn Bhd's LED Wafer Fabrication Plant here Tuesday.
He said the LED products are mainly exported to Japan, the United States, Singapore, Germany and Taiwan.
In his speech, Mustapa said Osram Penang had been manufacturing LEDs for worldwide distribution, for more than 20 years.
He added that it had at present, the world's most advanced LED chip factory.
"This new wafer fabrication facility is operating in addition to the main plant in Regensburg, Germany, to manufacture LED chips using state-of-the-art nitride technology and meeting growing demand from high-volume lighting and consumer applications.
"With this expansion, it also becomes the first wafer fabrication plant for LEDs in Malaysia," he said.
The facility is also the company's first ever LED chip plant in Asia and currently, the most modern in the world.
The production facility in Penang also makes Osram Opto Semiconductors the first LED manufacturer with high-volume chip production facilities both in Europe and Asia.
-- BERNAMA
PS
Today is the Opening Ceremony of Osram Opto Semiconductor in Penang. Though I was invited but due to my current assignment, I could not go and thus I miss seeing a lot of old friends in Penang.
Tuesday, April 27, 2010
Sunday, April 25, 2010
China LED Street Lamp vision and market development 2009-2012 (十城万盏)
2009 is China’s entry point for LED development, LED adoption and early experimental volume manufacturing. From what we can see the support of China Government as a national policy as to push for LED implementation nation wide, China is well aware that by year 2020, it will be the World No.1 Consumption of crude oil and energy consumption in the world. There is a need for China to adapt the new technology in order to save the energy and to reduce emission.
National Energy Resource policy
Being a developing country, we need to have along term vision in preservation on the energy resource as national policy. Or there will be no competitive edge of manufacturing cost amongst all countries in the world as China will be forced to import oil of mega tons. Though we can not see many solid encouragement plans, minute implementation road map nor advice to the industry enterprisers from Beijing government on how to go for LED, we can see that this is an essential topic in all kind of energy consortiums and LED seminars nation wide as part of the preliminary promotion approach and direction. 2009 Will be an early step into the LED era and this is an experimental prelude for electronics industry to migrate into the LED industry.
Street Lighting in China
China has issued ordinance and recommendation for street lamp implementation as part of the national energy campaign so called “ 十城万盏” “Ten City Ten Thousand Lamp” for the year 2009. LED is one of the biggest topics amongst the Green industry. Solar by Silicon has been blamed for his huge electrical and water consumption during the manufacturing process and this has been going into a cold down stage before next move. I have visited a lot of factories in the China, many of them involve whole LED line manufacturing from Chip to lighting modules, building their own LED tubes, Illumination lamps, direct replacement for the CFL tubes and Light Modules.
Replacement for CFL tubes
There is direct replacement built with High Power LED with SMD solder reflow onto the main board. Most of the Sothern region has been building LED replacement CFL tubes in the past 5 years though in small scale at an experimental and research level, however, more and more people with solid experience in Lighting and electronics industry followers and expert transference from some of the Taiwanese LED factories will establish new factories in the Northern Region of China.
Obstacles
However there are a lot of road block :
1. Lack of standardization on the Lighting specification and hard to buy off.
2. First installation price is still High for the end users, especially to short-termism.
3. Reliability in large scale road installation is still a query.
4. Fog penetration and lighting coverage is still a challenge.
5. Internal competition on CFL product, the CFL supplier is also some of the LED makers.
6. Manufacturing Process is yet mature for Hi Power LED manufacturing. We understand that only one company* has such kind of process capability to build Hi Power LED using new technology in a full line solution provider.
7. This is still hard for the building construction and lighting firm to use the LED to replace traditional Incandescent lightings in a large scale.
A lot of LED, LED display billboards can be seen in Shanghai EXPO, despite, a lot of Government exhibitor of China still using the awful incandescent lamp in many of the interior lighting designs. Is it a bit ironic to the Government?
Through 2008 Olympia games, 2009 60th National Celebration and Shanghai Expo; LED has been revealed and this is in fact a very effective promotion for LED itself to all the public.
Competition
There are a lot of price and technology competitors in the LED makers in China, after years of Copy cat production, we have seen hundreds of K2 LED makers in the market, and their price is just faction of the original K2 of Lumields. Apparently they look the same, they function the same, but they might not perform the same. Who know who can sustain the light performance over the next 50,000 hours!? In such market environment, Lumileds has to drop K2 production.
In many of the LED applications, low quality copy cat K2 were being used, after a few thousand hours, some of the LEDs did not light up at all or went dim due to premature aging before the life cycle is terminated.. Partly due to the failure of external electronics circuitry, but most of the failure is the using of low quality LEDs why has bad heat dissipation capacity.
Some of the European installation such as the Dutch City halls has to replace them again after two years of usage as many of them fail to light up. Hong Kong MTR Airport Express interior LED illumination has almost 10% failure on those 5 mm Vertical LEDs in side the light modules this gives bad impression on the LED and hardly persuades the end customers to use LED widely.
IC manufacturer
Many large IC manufacturers are interested converting their exiting wafer equipment to run LED. As partly they are so keen to go into this profitable market and on their other hand IC seems not going to experience such a high growth rate as LED in coming 5 years.
Shortage of Manpower
Insufficient technical support in the LED factories, we have seen a lot of small factories is in fact running by merely 1-2 people who has been either previously working from some of the bigger LED firm and they had hard time to find the right people for LED production line maintenance, There is difficulty to find the right people, who understands the manufacturing process of LED. There is no way to run a factory without proper skillful technician.
Remuneration for engineers
There are a lot of head hunting activities in these hot LED market in China. Some of the technicians are offered for RMB$10,000 a month in some of the North East Region, some of the middle manager’s salary is in the range of RMB$20,000-50,000 per month if they are capability to manage the LED manufacturing house. This will drive the market to short term instability as the high labour cost will lose out come of the competitiveness for the LED Company to the large LED houses.
Taiwan technology transfer
There are a few Taiwanese commonly has been announced plan to invest and run company with the local China factories, partly the Taiwanese as quid pro quo with local labor resources and cost benefit in China. China will be likely to take this as a learning process on the Taiwan LED manufacturing technology. Taiwanese LED makers are good at vertical integration. This is because they have been the strongest on LED manufacturing since the 80’s. The have all the experience in bonding process, equipment selection, process control and material vertical integration and staff management.
However under this relation, the China side may take a few years time to pick up the process know-how, Chip knowledge and manufacturing experience on LED from The Taiwanese.
Understand oneself
To understand one’s capacity is the prime factor to win the market, China LED factory should understand themselves on their level of technology capability. They are the third tier of the technology. The Western world has been dominating the technology and they have earned good reputation on LED as a branding. Their LED is being used as industrial standard. European and American LED are enjoying the highest selling price through stable quality and good reliability. However, this technology will sooner be coming less prominent after a few years and there are more and more Taiwanese and Chinese Companies would, on their other hand, with the maturity of the bonder equipment, and the total solution where company* is selling to the LED makers, the company can slowly developing their own recipes in the LED manufacturing with best cost performance in order to survive and to make profit.
Major Investment in China
Epistar and Liteon will set-up a new production line in Chang Zhou for LED assembly.
UMC will start a LED assembly factory in Shan Dong, with initial investment of USD$1.6M, the first installation will be some MOCVDs.
2010 vision
The technology maturity and scale of the vertical integration would drive the price of LED lower and such continuous move will push LED into an enormous market in 2010.
From what we can see that 2010 will be the having 300% growth as comparing with 2009, all the front and back equipment supplier shipment indicates that the market is very hot in 2009, Those Big Company like Aixtrons and Veeco who representing the unsurpassed leading quality equipment in front is working out way to increase their capacity to meet the new equipment demand.
Internal Competition.
With the ASP drop of 15% a year, more billion dollar investment multinational company announced to invest on LED in China, inevitably more competition will force the collaboration of smaller individual or smaller scale manufacturers to merge to further invest in order to survive in such harsh price competition. If there is no technology differentiation amongst those smaller companies, or there is not sufficient scale in vertical integration nevertheless, this will be soon be eliminated at the price war. However this only will happen after a few years when there is more or less a full picture of the LED market, price and players are stabilized.
CFL Supplier
The LED manufacturing cost reduction programme in order to debut themselves as leader in CFL and LED as well in the world wide market. On the other hand CFL is improving their performance. The mercury contamination of a CFL would contaminate tons of water at the end of the tubes. This will push the LED to be a prominent replacement for CFL as faster speed. Philips and Osram as the World’s largest CFL suppler will not hand off on the producing the best reliable, powerful LED at a reasonable competitive price for the market. In order to differentiate their cost advantage over the China Supplier. Being manufacturing in Malaysia, they might have to plan for serious cost reduction, adoption of new manufacturing Process, working with world leading LED equipment manufacturer for special powerful LED manufacturing Equipment.
Supplier performance on their 6” wafer will becoming dominant in the wafer epitaxial growth, There will be a lot of impact on the challenge on the LED sorter equipment.
Technology support
China Will remain the world largest LED manufacturing centre Tomorrow as it is today.
There is a need for government support in the research and development of LED.
There should have certain Optoelectronics and LED courses in Universities and technical institutes of China.
Ten Cities and Ten Thousand LED lamps
There are 222,000 LED Lamps installed in 2009, and there will be 1120,000 street lamps in 2010 and 2011. the Number is VERY small in the Cities of China but we can see there is a Tremendous Growth 500%... This is a index for us to work into these LED market. The Only concern is if we have the right food chain in supporting this kind of growth Rate.
Attached the Cities plan for the LED street lamp installation, being the first LED City Tian Jin was overtaken by Wei Feng in Shan Dong by number of installation. Wei Feng is the World Famous Kite City as the world Kite Competition is held in Wei Feng every April.
Vision for LED market 2010-2012
The market will continue to be hot as we are in the last Quarter 2009 and Q1 2010.
Back light will be the major contribution. The next hot driver for LED is the street lighting and indoor illumination lighting. We would see that there will take time for China to establish this market momentum, viewing that The major players in the world is investing huge amount of money in the factory set-up in China. This will create certain chain actions to lead and bring the local manufacturers to participate.
The year 2010 will be another years, more LED products will be found in the shelves in Supermarket. More people will be alert of the benefit of using LED in money saving and reduction of emission. The Whole life cycle would be speed up at, ASP will drop more abruptly. Bigger investment plan would be seen in China for LED manufacturers.
Feverip
PS
* denotes the World Largest Semiconductor Equipment Supplier : ASM assembly Automation LTD. Located in Singapore and Hong Kong.
Wednesday, April 21, 2010
Soraa and Kaai, an All Star LED Company
What makes the companies intriguing are the founders Shuji Nakamura, Stephen DenBaars and some of the ex-staff from Lumileds and Cree. In Japan LED circle, Shuji Nakamura is a major celebrity. Nakamura invented the blue LED in the early '1993 while working for Nichia.
Nakamura also made history by suing his employer, which gave him a bonus of around $200 for his invention, and winning in court. The somewhat un-Japanese action on Nakamura's part resulted in a settlement in the millions. He later became a professor at the University of California at Santa Barbara. He also won the Millennium Technology Prize. (Refer to the interesting biography of Nakamura by Bob Johnstone called Brilliant I introduced beginning of the Month).
Stephen DenBaars, a professor of material science at the University of California at Santa Barbara, is one of the leading researchers on LEDs. DenBaars has said that if 25 percent of the lightbulbs in the U.S. were converted to LEDs putting out 150 lumens per watt (higher than the commercial standard now), the U.S. as a whole could save $115 billion in utility costs, cumulatively, by 2025. "They (Nakamura and DenBaars) found the next breakthrough in LEDs in 2000 and they have been working on it for seven years," said Tamer. Tamer, who formerly worked at Broadcom, will primarily focus on energy-efficiency investments. Earlier this month, for instance, the firm announced it has an investment in EcoMotors, which is developing diesel engines that could get 100 miles per gallon.
Let's watch out for the possibly brightest LED ever made by Soraa!
Feverip
Illumitex LED, an advance new lens technology for more Lumens
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“What Illumitex has achieved is a fundamental breakthrough in delivering the most usable lumens to the task surface, thus providing unrivaled overall lighting system efficiency," said Matt Thomas, CEO of Illumitex. "We have reinvented the basic die and package structure to create the industry’s most optically advanced LED. Our technology allows us to deliver perfectly uniform light exactly where the customer wants it.”
Their Characteristic of LED is small footprint, easy scallable for a High Power point souce for Lighing Illumination.
Feverip
Monday, April 5, 2010
How a LED Chip is Made!?
There is a very easy reading essay in Shuji Nakamura's Book "Brilliant" teaches us how to make a LED.
"
The conventional method of making LEDs, liquid phase epitaxial could not grow films for high enough quality and sufficient thinness..
There are two more modern alternatives. Both were capable of growing films of material just a few atoms thick. One molecular beam epitaxial works via vacuum evaporation. MBE is especially popular with academic scientist. It can product small quantities of material, enough for researchers to extract data based on what they can write and published papers. But MBE requires a ultrahigh vacuum, has very slow growth rates, and is difficult to scale up. In the opinion of most people, Shinji included, the method is not suitable for mass production.
That Left MOCVD, which does not need a high vacuum and can be applied to the factory floor. The choice was thus, as they say in Silicon valley, a no-brainer, Shuji selected MOCVD without hesitation, But he had little idea of how MOCVD was done.
By a stroke of good fortune, it just so happened that one of Japan. Leading Experts on the technique was an old acquaintance of his from Tokushima University. Though Shiro Sakai had been two years Sakai’s senior, they had worked together in the same laboratory, and Shuji knew him well.. In the interviewing years, Sakai, now a professor at Tokushima, had become well known for his expertise n MOCVD, Now he was on sabbatical at the University of Florida. During the Summer holiday of 1987, he returned to Japan. Nakamura went to see Sakai to ask hi advice on how to learn MOCVD.
When Sakai returned to Japan for a week at the end of 1987. Nakamura invited hi to Visit Nichia. There, the professor explained to Ogawa the significance of MOCVD as a Crucial tool for the production of state-of-the-Arts LEDs. At this meeting, blue LEDS were not mentioned, Sakai recommended that Nichia should send Nakamura for a year to the engineering school at the University of Florida, where he was currently on sabbatical. A deal was arranged: Nakamura would learn MOCVD under Sakai’s tutelage. In return, Nichia Would donate around $100,000 to fund Sakai’s research.
To make a chip the size of a grain of sand takes a mighty big box. A typical MOCVD system is almost as big as a shipping container and costs well over a million dollars. Seen from outside, MOCVD equipment looks rather dull, like a row of office cabinets. Peek behind the bland-looking doors, however, and you will discover a bewildering assemblage f tanks, pumps and valves connected by what appears t be several miles of thin, stainless steel pipe. At the end of cabinets is a rack containing a computer that runs the recipes for growing LEDs. These are programs that, with exquisite precision, control the pressure and flow of gases, while monitoring the temperature and the rate at which the thin films of crystal grow.
The heart of MOCVD system is through a little window in one of the cabinet doors, it its reactor chamber. This is a cylinder about the size of a cookie jar, made of quartz in some systems, of metal in others. It may, be positioned either horizontally or perpendicularly. The chamber is remarkably small in comparison to the whole. It occupies perhaps 3 or 4 percents of the total space. Inside the jar there is a graphite chuck, mounted on a little pedestal, here sits the wafer on which the thin films are growth. The Chuck is connected via a thermocouple that monitors the growth temperature, to a heater. T grow Gallium Nitride, the wafer is heated to between 1,000 and 1,200 degrees Celsius. At which point it grows bright golden-orange, In case of quartz chambers, the heat comes form copper coils would round the jar. An exhaust system, typically a vacuum pump, completes the process, It sucks the unused gases out of the reactor chamber, flushing them away to a scrubber for disposal.
For more than twenty years LED were grown by one of the two methods, liquid phase epitaxy (LPE) or vapour phase epitaxy (VPE). Epitaxy simply means stacking crystal layer upon crustal exactly the same orientation, like piles of eggs trays, But when it came to growing hg-quality thin films and quantum wells, which require abrupt atomic level transitions from one layer to the next, both processes were too crude. For example, an LPE system consists of a quartz tube in which are .lined up with little graphite dishes called, because of their cigar like shape, “boats, ” Each boat contains a different semiconductor material that is heated until it melts. You slide your wafer along the tube, leaving it to sit a while on top of each boat. Cooling causes some of the materials go precipitate onto the surface of the wafer. LPE produces relatively thick layers, and the boundaries between them are gradually rather than sharply defined. Precise control move thickness almost impossible to achieve.
MOCVD (sometimes, confusingly, also known as MOVPD) system because the method of choice for growing high-brightness devices, original red LEDs, in the mid-1980’s MOCVD accomplished the abrupt transition between layers by allowing the crystal grower to run two mixes of gases through the system simultaneously. While using mix A to grow a film in the reactor, you have all the gases for mix B flowing directly to exhaust, Then, at just the right moment, you switch mix A to the moments. All you hear is sound of the compressed air-driven pneumatic valves. They open and close in quick succession- phsst, phsst, phsst, phsst-et voila! You have grown a quantum well.
So much for vapor deposition, Now we come to metal organic chemicals, why it is necessary to sue such fancy-sounding stuff instead of ordinary metal? The answer is that, in their vapor ;phase neither aluminum, gallium, nor Indium- the three most common metals use in growing bright blue (and Red and green) LEDs- can muster sufficient vapor to be picked up the carried there, in organic form. To pump up the vapour pressure, organize chemical such a Methyl groups are attached to the metals Gallium becomes trimethyl gallium; the positive-types dopant magnesium becomes bis(Cyclopentadienyl) magnesium, mercifully abbreviated as CP2MG. The carrier gas in hydrogen. It is kept Flowing through the system at a rate of many litres per minute. During the travels, the hydrogen bubbles through the temperature of the compounds. Which it transports to the reactor. When the com[pound gases get to the hot zone. They lose their methyl groups. The nitrogen or Gallium nitrides arrives at the jar in the form ammonia.
The heat decomposes the gases. Leaving nitrogen atoms hot to trot their gallium Partners.
The process of growing a gallium nitride LED begins by heating the sapphire wafer to a very high temperature. Once hot, you clean the surface by flowing nitrogen over it. Then you drop the temperature way down to maybe 500 degrees Celsius to grow the first layer, the so called nucleation, or buffer, layer. This is a thin film, typically of gallium or aluminum nitride and juts 50 to 100 atoms thick, that is grown directly on the wafer. The buffer layer is amorphous, that is lacking a crystalline structure. When you heat it up, the surface of this amorphous layer becomes very lumpy as nucleation islands oriented to the surface of the sapphire start to form, As you reach higher temperatures, however, these islands grow together laterally, to form a smooth , mirror-like layer of gallium or aluminum nitride., One of the secrets of growing high-quality GaN is being abe to control exactly how this nucleation layer is deposited, how is crystallizes, and how it grows together during the heat-up step.
On top of the nucleation layer, you deposit plain vanilla (i.e., undoped) gallium nitride.
Next comes a layer of negative-types gallium nitride, wit silane as the electron-donaing dopant. This is followed by a layer of negatively doped aluminum gallium nitride, a compound with a wider bandgap than GaN. This layer plus another . positively doped layer of AlGaN o the other side serve to confine the charge carriers within the active _i.e. light emitting) layer of the device, Then you drop the temperature down from 1,000-1,200 degrees Celsius to 750-850 degrees Celsius s that you can grow an indium gallium nitride quantum well. You grow, say ., 20 angstroms of InGaN, then maybe 100 angstronms of GaN, then repeat the process for as many quantum wells as your recipe calls for, adjusting the amount of indium to produce the desired wavelength of light. The more indium you include, the greener the output will be. After growing the last combo of InGaN+GaN, you crank the temperature back up and deposit your other confining layer of positively doped aluminum gallium nitride. Then you cap the whole thing off with a layer of positive-type gallium nitride using magnesium as the hole-donating dopant, That completed the device.
In a typical growth run, the whole process takes anywhere between two and a half hours and hour hours. If you load your wafer first things in the morning just as the coffee is brewing. You will gte the growth sun out around lunchtime. You should schedule another run around two o’clock and have it out before dinner. Between runs, you have to clean the reactor b baking it out at high temperature. In the R&D lab, two runs is not a bad day. On the production line, four growth runs in a twenty-four-hour period is consider pretty good going. A large production –line reactor may contain a platter with a many as one hundred wafer on board.
The growth process itself is not in the least dramatic. You can hear faint hums and hisses from the pumps and the valves, but that’s about it. The only smell MOCVD machine gives off is a subtle whiff of burnt reactants that emanates from inside the jar, if you smell anything else—ammonia, for example- that means there is a leak, This is a good time to leave the lab. Quickly.
"
"
The conventional method of making LEDs, liquid phase epitaxial could not grow films for high enough quality and sufficient thinness..
There are two more modern alternatives. Both were capable of growing films of material just a few atoms thick. One molecular beam epitaxial works via vacuum evaporation. MBE is especially popular with academic scientist. It can product small quantities of material, enough for researchers to extract data based on what they can write and published papers. But MBE requires a ultrahigh vacuum, has very slow growth rates, and is difficult to scale up. In the opinion of most people, Shinji included, the method is not suitable for mass production.
That Left MOCVD, which does not need a high vacuum and can be applied to the factory floor. The choice was thus, as they say in Silicon valley, a no-brainer, Shuji selected MOCVD without hesitation, But he had little idea of how MOCVD was done.
By a stroke of good fortune, it just so happened that one of Japan. Leading Experts on the technique was an old acquaintance of his from Tokushima University. Though Shiro Sakai had been two years Sakai’s senior, they had worked together in the same laboratory, and Shuji knew him well.. In the interviewing years, Sakai, now a professor at Tokushima, had become well known for his expertise n MOCVD, Now he was on sabbatical at the University of Florida. During the Summer holiday of 1987, he returned to Japan. Nakamura went to see Sakai to ask hi advice on how to learn MOCVD.
When Sakai returned to Japan for a week at the end of 1987. Nakamura invited hi to Visit Nichia. There, the professor explained to Ogawa the significance of MOCVD as a Crucial tool for the production of state-of-the-Arts LEDs. At this meeting, blue LEDS were not mentioned, Sakai recommended that Nichia should send Nakamura for a year to the engineering school at the University of Florida, where he was currently on sabbatical. A deal was arranged: Nakamura would learn MOCVD under Sakai’s tutelage. In return, Nichia Would donate around $100,000 to fund Sakai’s research.
To make a chip the size of a grain of sand takes a mighty big box. A typical MOCVD system is almost as big as a shipping container and costs well over a million dollars. Seen from outside, MOCVD equipment looks rather dull, like a row of office cabinets. Peek behind the bland-looking doors, however, and you will discover a bewildering assemblage f tanks, pumps and valves connected by what appears t be several miles of thin, stainless steel pipe. At the end of cabinets is a rack containing a computer that runs the recipes for growing LEDs. These are programs that, with exquisite precision, control the pressure and flow of gases, while monitoring the temperature and the rate at which the thin films of crystal grow.
The heart of MOCVD system is through a little window in one of the cabinet doors, it its reactor chamber. This is a cylinder about the size of a cookie jar, made of quartz in some systems, of metal in others. It may, be positioned either horizontally or perpendicularly. The chamber is remarkably small in comparison to the whole. It occupies perhaps 3 or 4 percents of the total space. Inside the jar there is a graphite chuck, mounted on a little pedestal, here sits the wafer on which the thin films are growth. The Chuck is connected via a thermocouple that monitors the growth temperature, to a heater. T grow Gallium Nitride, the wafer is heated to between 1,000 and 1,200 degrees Celsius. At which point it grows bright golden-orange, In case of quartz chambers, the heat comes form copper coils would round the jar. An exhaust system, typically a vacuum pump, completes the process, It sucks the unused gases out of the reactor chamber, flushing them away to a scrubber for disposal.
For more than twenty years LED were grown by one of the two methods, liquid phase epitaxy (LPE) or vapour phase epitaxy (VPE). Epitaxy simply means stacking crystal layer upon crustal exactly the same orientation, like piles of eggs trays, But when it came to growing hg-quality thin films and quantum wells, which require abrupt atomic level transitions from one layer to the next, both processes were too crude. For example, an LPE system consists of a quartz tube in which are .lined up with little graphite dishes called, because of their cigar like shape, “boats, ” Each boat contains a different semiconductor material that is heated until it melts. You slide your wafer along the tube, leaving it to sit a while on top of each boat. Cooling causes some of the materials go precipitate onto the surface of the wafer. LPE produces relatively thick layers, and the boundaries between them are gradually rather than sharply defined. Precise control move thickness almost impossible to achieve.
MOCVD (sometimes, confusingly, also known as MOVPD) system because the method of choice for growing high-brightness devices, original red LEDs, in the mid-1980’s MOCVD accomplished the abrupt transition between layers by allowing the crystal grower to run two mixes of gases through the system simultaneously. While using mix A to grow a film in the reactor, you have all the gases for mix B flowing directly to exhaust, Then, at just the right moment, you switch mix A to the moments. All you hear is sound of the compressed air-driven pneumatic valves. They open and close in quick succession- phsst, phsst, phsst, phsst-et voila! You have grown a quantum well.
So much for vapor deposition, Now we come to metal organic chemicals, why it is necessary to sue such fancy-sounding stuff instead of ordinary metal? The answer is that, in their vapor ;phase neither aluminum, gallium, nor Indium- the three most common metals use in growing bright blue (and Red and green) LEDs- can muster sufficient vapor to be picked up the carried there, in organic form. To pump up the vapour pressure, organize chemical such a Methyl groups are attached to the metals Gallium becomes trimethyl gallium; the positive-types dopant magnesium becomes bis(Cyclopentadienyl) magnesium, mercifully abbreviated as CP2MG. The carrier gas in hydrogen. It is kept Flowing through the system at a rate of many litres per minute. During the travels, the hydrogen bubbles through the temperature of the compounds. Which it transports to the reactor. When the com[pound gases get to the hot zone. They lose their methyl groups. The nitrogen or Gallium nitrides arrives at the jar in the form ammonia.
The heat decomposes the gases. Leaving nitrogen atoms hot to trot their gallium Partners.
The process of growing a gallium nitride LED begins by heating the sapphire wafer to a very high temperature. Once hot, you clean the surface by flowing nitrogen over it. Then you drop the temperature way down to maybe 500 degrees Celsius to grow the first layer, the so called nucleation, or buffer, layer. This is a thin film, typically of gallium or aluminum nitride and juts 50 to 100 atoms thick, that is grown directly on the wafer. The buffer layer is amorphous, that is lacking a crystalline structure. When you heat it up, the surface of this amorphous layer becomes very lumpy as nucleation islands oriented to the surface of the sapphire start to form, As you reach higher temperatures, however, these islands grow together laterally, to form a smooth , mirror-like layer of gallium or aluminum nitride., One of the secrets of growing high-quality GaN is being abe to control exactly how this nucleation layer is deposited, how is crystallizes, and how it grows together during the heat-up step.
On top of the nucleation layer, you deposit plain vanilla (i.e., undoped) gallium nitride.
Next comes a layer of negative-types gallium nitride, wit silane as the electron-donaing dopant. This is followed by a layer of negatively doped aluminum gallium nitride, a compound with a wider bandgap than GaN. This layer plus another . positively doped layer of AlGaN o the other side serve to confine the charge carriers within the active _i.e. light emitting) layer of the device, Then you drop the temperature down from 1,000-1,200 degrees Celsius to 750-850 degrees Celsius s that you can grow an indium gallium nitride quantum well. You grow, say ., 20 angstroms of InGaN, then maybe 100 angstronms of GaN, then repeat the process for as many quantum wells as your recipe calls for, adjusting the amount of indium to produce the desired wavelength of light. The more indium you include, the greener the output will be. After growing the last combo of InGaN+GaN, you crank the temperature back up and deposit your other confining layer of positively doped aluminum gallium nitride. Then you cap the whole thing off with a layer of positive-type gallium nitride using magnesium as the hole-donating dopant, That completed the device.
In a typical growth run, the whole process takes anywhere between two and a half hours and hour hours. If you load your wafer first things in the morning just as the coffee is brewing. You will gte the growth sun out around lunchtime. You should schedule another run around two o’clock and have it out before dinner. Between runs, you have to clean the reactor b baking it out at high temperature. In the R&D lab, two runs is not a bad day. On the production line, four growth runs in a twenty-four-hour period is consider pretty good going. A large production –line reactor may contain a platter with a many as one hundred wafer on board.
The growth process itself is not in the least dramatic. You can hear faint hums and hisses from the pumps and the valves, but that’s about it. The only smell MOCVD machine gives off is a subtle whiff of burnt reactants that emanates from inside the jar, if you smell anything else—ammonia, for example- that means there is a leak, This is a good time to leave the lab. Quickly.
"
Friday, April 2, 2010
ASM LED Die Bonder AD830
With the vision of ASM top management led by ex CEO Patrick Lam who brought ASM into another fast growth era 1990… ASM introduced the world for the high throughput solution for LED market. The AD829 in 1996, followed by AD829A advanced versions in 2000. and AD8930 series in 2002, and AD830 in 2005...
With the advantage of having all kinds of packaging exposure, various sorts of LED products, ASM has equipped with all the features and process know-how onto this Current production of LED Epoxy High speed die bonder AD830, which is dominating the whole LED market.
All the major LED makers are using AD830 as their major runner for their LED product, the advantage if AD830 is fast, reliable, accurate with die placement accuracy of +/-1 mil and +/-3 degree, Cycle time for Small chip like 10mil x 10mil is 180 ms. An equivalent UPH of 18,000. It is equipped with Post bond inspection system that monitors the bonded unit at pre-set placement range…at a selected inspection scheme.
AD830 epoxy die bonder is driven by ASM proprietary technology of Linear motor, an US patent fully decoupled Bond head XY module, an Ultra Light Bond Arm that can run a speed of 10G… Driven by latest Module of Motion Control, Synchronized motion of Bond head and ejector system ensuring least minimum impact on the 3 mil thin chips.
In the LED market, there are a lot of rival or competitors for AD830, but, all the hidden technology of AD830 is not able to be copied in days, ASM is a low profile operating company, but the customer is not astonished by the yield 99.95% and MTBA >1 hour, and low down time of AD830. As only a Low profile branding company could bring the best debut of good quality product like not others.
If you are LED manufactures, only you can use the best equipment for manufacturing the brightest LEDs, contact ASM to book you machine AD830 as soon as you can.
HK Snob